My toilet runs intermittently (or constantly). Do I have to replace it?

Not necessarily. In most cases, either the flush valve or flapper can be replaced for very little money compared to replacing the whole toilet. However, like anything mechanical, toilets and faucets do wear out over time and should be replaced. If your fixtures are over 8-10 years old and you have had them repaired in the past, you may want to consider replacements.